Can I create an oval spotlight?
The light is a source of emission and can not be scaled. While the dotted line helper is forced to conform to the scale, the render will ignore it.

Two possible ez solutions:

1.) Use a stencil and shadows. literally make a plane with an oval shape in it and place it in front of the light. Make sure shadows are enabled. You can make the plane only cast shadows so that it will not appear in the render.

2.) Shine the light at a different angle. Like pointing a flashlight almost parallel against a wall, the shape of the light will appear to stretch as the light travels further and further to reach the wall's surface.